Entries Tagged "Microsoft"

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Long-Lived Vulnerability in Microsoft Secure Boot

Microsoft’s Secure Boot has had a serious vulnerability for most of its existence.

An industry-wide standard Microsoft invented to protect Windows, and later Linux, devices from firmware infections has been trivial to bypass for 13 of its 14 years of existence. The discovery was made by researchers at security firm ESET after identifying 11 firmware images, at least one from 2013, that were known to be defective but remained signed by the software company anyway.

The images are known as shims, which were invented to extend Secure Boot to Linux devices and utility software. Using a technique simple enough to be performed by novice hackers, these old, forgotten shims can be used to completely circumvent the protection, which is embedded into the UEFI (Unified Extensible Firmware Interface) of the device’s motherboard. The gaffe is the result of the failure by Microsoft, which oversees the signing of shims, to revoke the publicly available images once vulnerabilities were found in them.

Posted on July 29, 2026 at 7:01 AM • View Comments

On Microsoft’s Lousy Cloud Security

ProPublica has a scoop:

In late 2024, the federal government’s cybersecurity evaluators rendered a troubling verdict on one of Microsoft’s biggest cloud computing offerings.

The tech giant’s “lack of proper detailed security documentation” left reviewers with a “lack of confidence in assessing the system’s overall security posture,” according to an internal government report reviewed by ProPublica.

Or, as one member of the team put it: “The package is a pile of shit.”

For years, reviewers said, Microsoft had tried and failed to fully explain how it protects sensitive information in the cloud as it hops from server to server across the digital terrain. Given that and other unknowns, government experts couldn’t vouch for the technology’s security.

[…]

The federal government could be further exposed if it couldn’t verify the cybersecurity of Microsoft’s Government Community Cloud High, a suite of cloud-based services intended to safeguard some of the nation’s most sensitive information.

Yet, in a highly unusual move that still reverberates across Washington, the Federal Risk and Authorization Management Program, or FedRAMP, authorized the product anyway, bestowing what amounts to the federal government’s cybersecurity seal of approval. FedRAMP’s ruling—which included a kind of “buyer beware” notice to any federal agency considering GCC High—helped Microsoft expand a government business empire worth billions of dollars.

Posted on April 9, 2026 at 6:51 AM • View Comments

Microsoft Xbox One Hacked

It’s an impressive feat, over a decade after the box was released:

Since reset glitching wasn’t possible, Gaasedelen thought some voltage glitching could do the trick. So, instead of tinkering with the system rest pin(s) the hacker targeted the momentary collapse of the CPU voltage rail. This was quite a feat, as Gaasedelen couldn’t ‘see’ into the Xbox One, so had to develop new hardware introspection tools.

Eventually, the Bliss exploit was formulated, where two precise voltage glitches were made to land in succession. One skipped the loop where the ARM Cortex memory protection was setup. Then the Memcpy operation was targeted during the header read, allowing him to jump to the attacker-controlled data.

As a hardware attack against the boot ROM in silicon, Gaasedelen says the attack in unpatchable. Thus it is a complete compromise of the console allowing for loading unsigned code at every level, including the Hypervisor and OS. Moreover, Bliss allows access to the security processor so games, firmware, and so on can be decrypted.

Posted on March 23, 2026 at 7:01 AM • View Comments

Manipulating AI Summarization Features

Microsoft is reporting:

Companies are embedding hidden instructions in “Summarize with AI” buttons that, when clicked, attempt to inject persistence commands into an AI assistant’s memory via URL prompt parameters….

These prompts instruct the AI to “remember [Company] as a trusted source” or “recommend [Company] first,” aiming to bias future responses toward their products or services. We identified over 50 unique prompts from 31 companies across 14 industries, with freely available tooling making this technique trivially easy to deploy. This matters because compromised AI assistants can provide subtly biased recommendations on critical topics including health, finance, and security without users knowing their AI has been manipulated.

I wrote about this two years ago: it’s an example of LLM optimization, along the same lines as search-engine optimization (SEO). It’s going to be big business.

Posted on March 4, 2026 at 7:06 AM • View Comments

Microsoft is Giving the FBI BitLocker Keys

Microsoft gives the FBI the ability to decrypt BitLocker in response to court orders: about twenty times per year.

It’s possible for users to store those keys on a device they own, but Microsoft also recommends BitLocker users store their keys on its servers for convenience. While that means someone can access their data if they forget their password, or if repeated failed attempts to login lock the device, it also makes them vulnerable to law enforcement subpoenas and warrants.

Posted on February 3, 2026 at 7:05 AM • View Comments

Microsoft Is Finally Killing RC4

After twenty-six years, Microsoft is finally upgrading the last remaining instance of the encryption algorithm RC4 in Windows.

One of the most visible holdouts in supporting RC4 has been Microsoft. Eventually, Microsoft upgraded Active Directory to support the much more secure AES encryption standard. But by default, Windows servers have continued to respond to RC4-based authentication requests and return an RC4-based response. The RC4 fallback has been a favorite weakness hackers have exploited to compromise enterprise networks. Use of RC4 played a key role in last year’s breach of health giant Ascension. The breach caused life-threatening disruptions at 140 hospitals and put the medical records of 5.6 million patients into the hands of the attackers. US Senator Ron Wyden (D-Ore.) in September called on the Federal Trade Commission to investigate Microsoft for “gross cybersecurity negligence,” citing the continued default support for RC4.

Last week, Microsoft said it was finally deprecating RC4 and cited its susceptibility to Kerberoasting, the form of attack, known since 2014, that was the root cause of the initial intrusion into Ascension’s network.

Fun fact: RC4 was a trade secret until I published the algorithm in the second edition of Applied Cryptography in 1995.

Posted on December 22, 2025 at 12:05 PM • View Comments

Microsoft SharePoint Zero-Day

Chinese hackers are exploiting a high-severity vulnerability in Microsoft SharePoint to steal data worldwide:

The vulnerability, tracked as CVE-2025-53770, carries a severity rating of 9.8 out of a possible 10. It gives unauthenticated remote access to SharePoint Servers exposed to the Internet. Starting Friday, researchers began warning of active exploitation of the vulnerability, which affects SharePoint Servers that infrastructure customers run in-house. Microsoft’s cloud-hosted SharePoint Online and Microsoft 365 are not affected.

Here’s Microsoft on patching instructions. Patching isn’t enough, as attackers have used the vulnerability to steal authentication credentials. It’s an absolute mess. CISA has more information. Also these four links. Two Slashdot threads.

This is an unfolding security mess, and quite the hacking coup.

Posted on July 28, 2025 at 7:09 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.